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61.
The time dependence of the orientation of Earth's inner core relative to the mantle was determined using a recently discovered 10-degree tilt in the axis of symmetry of the inner core's seismic-velocity anisotropy. Two methods of analyzing travel-time variations for rays traversing the inner core, on the basis of 29 years of data from the International Seismological Centre (1964-1992), reveal that the inner core appears to rotate about 3 degrees per year faster than the mantle. An anomalous variation in inner-core orientation from 1969 to 1973 coincides in time with a sudden change ("jerk") in the geomagnetic field.  相似文献   
62.
The fertilization management of the rice crop in Piedmont was analyzed at a regional scale, and the agronomic and environmental sustainability of the actual fertilization strategy of rice was evaluated through the analysis of its effect on the soils and waters quality. On average, a total amount of 127 kg ha−1 of N, 67 kg ha−1 of P2O5 and 161 kg ha−1 of K2O were supplied to the rice crop. In most cases N and P fertilization was rather well balanced with crop removal. The N balance was in the range ±50 kg for 77% of the surface. The low concentration of N in the groundwater reflected the small N surplus. P fertilization resulted to be smaller than removal for 53% of the surface. Nevertheless, the soil extractable P was very high, probably because of former higher P inputs. This resulted in a high concentration in water courses and aquifers. The K fertilization was excessive (surplus >100 kg ha−1) for 53% of the surface, but most soils showed a low K content. K is probably contributing to nutrient leaching to a great extent. The average soil organic matter (SOM) content of paddy fields was higher than that of normally-cultivated soils in Piedmont, and the C/N was higher, owing to the low mineralization rate in waterlogged conditions. The SOM content was in relation with the management of the crop residues, as the tradition of burning straw after harvest was still widespread on 65% of the paddy surface.  相似文献   
63.
The potential of fruit storage facilities that are contaminated with the widely used chemical antioxidant diphenylamine to cross-contaminate untreated apples (Malus × domestica Borkh.) was studied. A new sample preparation method identified the storage room paint, contaminated from past treatments, as the major source of cross-contamination in the analyzed facilities. Diphenylamine amounts of up to 917 g were found in a single storage room and were shown to correlate with the extent of cross-contamination on stored apples. Our data support a diffusion-based mechanism where the wall paint releases the antioxidant to the storage room atmosphere even years after the last treatment. Given the extent of cross-contamination found in our model experiments and under commercial storage conditions, we deduce a significant risk of exceeding the potentially upcoming maximum residue level of 0.01 mg kg(-1) on stored fruit in contaminated rooms even years after the last diphenylamine treatment.  相似文献   
64.
Improving our understanding of the mechanisms controlling the corpus luteum (CL) and its role in regulating the reproductive cycle should lead to improvements in the sustainability of today's global animal industry. The corpus luteum (CL) is a transient endocrine organ composed of a heterogeneous mixture steroidogenic, endothelial and immune cells, and it is becoming clear that immune mechanisms play a key role in CL regulation especially in luteolysis. Toll‐like receptors (TLR) mediate innate immune mechanisms via the production of pro‐inflammatory cytokines, especially within various tissues, although the role of TLR within CL remains unknown. Thus, the objectives of this study were to characterize TLR mRNA expression in the CL during the oestrous cycle and in pregnancy (day 30–50), and to examine the role of TLR signalling in luteal cells. Corpora lutea were collected at various stages of the cycle and pregnancy and analysed for TLR and cytokine mRNA expression. In addition, luteal cells were cultured with the TLR4 ligand (lipopolysaccharide, LPS) for 24 h to evaluate the role of TLR4 in regulating luteal function. Toll‐like receptors 1, 2, 4, 6, tumour necrosis factor alpha (TNF), interferon gamma (IFN‐G), and interleukin (IL)‐12, mRNA expressions were greatest in regressing CL compared with earlier stages (p < .05), whereas no change was observed for IL‐6 mRNA expression. Cytokine mRNA expression in cultured luteal cells was not altered by LPS. Based on these data, one or more of the TLRs found within the CL may play a role in luteolysis, perhaps via pro‐inflammatory cytokine mRNA expression.  相似文献   
65.
Data were 876 birth records and 727 weaning records of straightbred and F3 crossbred calves produced in the third generation of a five-breed diallel. Among straightbreds at birth, Holstein calves were heaviest and widest at the shoulders and hips. Jersey calves were lightest and narrowest at the hips, and Brahman calves were narrowest at the shoulders. Holstein crosses tended to be larger at birth than crosses among other breeds. Among straightbreds at weaning, Holstein calves were heaviest and tallest, and Hereford calves were lightest and shortest. Angus calves had the highest survival to weaning rate, and Holstein calves had the lowest survival rate. Among crossbred calves, Holstein crosses tended to be larger at weaning. Estimates of average heterosis retained for birth characters were not significant. Significant breed mean heterosis retention was observed for birth weight, shoulder width, and hip width of Hereford calves and for shoulder width and hip width of Holstein calves. Estimates of average heterosis retained for weaning weight and height were 6.1 kg (P less than .01) and 1.02 cm (P less than .05), respectively. In general, estimates of specific and average heterosis retained for survival to weaning were nonsignificant. Significant breed mean heterosis was observed for weaning weight and height of Brahman, Hereford, and Holstein calves and for survival to weaning of Hereford, Holstein, and Jersey calves.  相似文献   
66.
Reproductive and calving records of 611 cows from F1 and F2 generations from a diallel mating system with Angus, Brahman, Hereford, Holstein and Jersey were examined. The inter se matings were by artificial insemination, and each cow had three or four parturitions. Dependent variables included weight, hip weight at first calving, age at first calving, gestation length and calving interval. Brahmans were the heaviest, tallest and oldest purebred at first calving. Crossbred Brahman females tended to be older than other crosses at first calving. Purebred Brahmans and one-half Brahman crosses also had the longest gestation lengths and calving intervals. First-gestation (F1) crossbred cows were 18 kg heavier (P less than .05), 2.0 cm taller (P less than .01) and 35 d younger (P less than .05) at first calving than contemporary straightbreds. Average maternal heterosis for height at calving was significant (1.4 cm; P less than .05); however, estimates of specific and average maternal heterosis for measurements taken at first calving were generally nonsignificant. Estimates of specific and average individual and maternal heterosis were generally small and nonsignificant for gestation length and calving interval.  相似文献   
67.
This study aimed to evaluate the effectiveness of hormonal treatments on ovarian activity and reproductive performance in Barki and Rahmani ewes during non‐breeding season. Forty‐eight multiparous ewes, 24 Barki and 24 Rahmani ewes were divided into two groups, 12 lactating and 12 dry ewes for each breed. Controlled internal drug release (CIDR) device was inserted in all ewes for 14 days in conjunction with intramuscular 500 IU equine chronic gonadotrophin (eCG) at day of CIDR removal. Data were analysed using PROC MIXED of SAS for repeated measures. Breed, physiological status and days were used as fixed effects and individual ewes as random effects. Barki ewes recorded higher (p < .05) total number of follicles, number of large follicles, serum estradiol concentration and estradiol: progesterone (E2:P4) ratio compared to Rahmani ewes. Lactating ewes recorded higher (p < .05) number of small follicles and lower concentration of total antioxidant capacity (TAC) compared to dry ewes. Number and diameter of large follicles recorded the highest (p < .05) values accompanied with disappearance of corpora lutea at day of mating. Serum progesterone concentration recorded lower (p < .05) value at day of mating and the highest (< .05) value at day 35 after mating. CIDR‐eCG protocol induced 100% oestrous behaviour in both breeds, but Rahmani ewes recorded longer (< .05) oestrous duration compared to Barki. Conception failure was higher (< .05) in Barki compared to Rahmani ewes. In conclusion, CIDR‐eCG protocol was more potent in improving ovarian activity in Barki compared to Rahmani ewes, but this protocol seems to induce hormonal imbalance in Barki ewes that resulted in increasing conception failure compared to Rahmani ewes.  相似文献   
68.
The study was designed to evaluate the influence of genetic origin on rabbit seminal plasma protein profile variation along the year. Seminal plasma of rabbits from line A (maternal line) and R (paternal line) collected during a natural year was subjected to polyacrylamide gel electrophoresis (SDS‐PAGE). The electrophoretic profile of rabbit seminal plasma resulted in multiple protein bands of different intensity ranging from 9 to 240 kDa. Results showed that seven protein bands were significantly different between genetic lines, and among these, three protein bands were significantly different between seasons. The differentially expressed proteins were identified by MALDI‐TOF/TOF or LC‐MS/MS analysis and were the following ones: FAM115E‐like (220, 113 and 59 kDa), ectonucleoside triphosphate diphosphohydrolase 3 isoform X2 (72 kDa), annexin A5 (32 kDa), lipocalin allergen Ory c 4 precursor (19 kDa), and haemoglobin subunit zetalike (13 kDa) between genetic lines and FAM115E‐like (113 kDa), haemoglobin subunit zetalike (13 kDa) and β‐nerve growth factor (12 kDa) between seasons. These results indicate that proteins from rabbit seminal plasma are under both seasonal control and genetic control. Furthermore, the differential presence of these proteins could be one of the causes explaining the differences observed in fertility and seminal parameters between these two lines in earlier studies.  相似文献   
69.
70.
Joining immature gamete cryopreservation and germinal vesicle transplantation (GVT) technique could greatly improve assisted reproductive technologies in animal breeding and human medicine. The present work was aimed to assess the most suitable cryopreservation protocol between slow freezing and vitrification for immature denuded bovine oocytes, able to preserve both nuclear and cytoplasmic competence after thawing. In addition, the outcome of germinal vesicle transfer procedure and gamete reconstruction was tested on the most effective cryopreservation system. Oocytes, isolated from slaughterhouse ovaries, were stored after cumulus cells removal either by slow freezing or by vitrification in open pulled straws. After thawing, oocytes were matured for 24 h in co-culture with an equal number of just isolated intact cumulus enclosed oocytes, and fixed in order to evaluate the stage of meiotic progression and cytoskeleton organization. Our results showed that after warming, vitrified oocytes reached metaphase II (MII) in a percentage significantly higher than oocytes cryopreserved by slow freezing (76.2% and 36.5% respectively, p < 0.05). Moreover, vitrification process preserved the organization of cytoskeleton elements in a higher proportion of oocytes than slow freezing procedure. Therefore vitrification has been identified as the elective method for denuded immature oocytes banking and it has been applied in the second part of the study. Our results showed that 38.3% of oocytes reconstructed from vitrified gametes reached the MII of meiotic division, with efficiency not different from oocytes reconstructed with fresh gametes. We conclude that vitrification represents a suitable method of GV stage denuded oocyte banking since both nuclear and cytoplasmic components derived from cryopreserved immature oocytes can be utilized for GVT.  相似文献   
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